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Reaction synthesis of bulk intermetallic materials from cold spray deposits from binary powders containing iron
Dyčková, Lucie ; Krajňáková, Petra (referee) ; Jan, Vít (advisor)
This thesis deals with reaction synthesis of materials Fe–Al, Fe–Cu and Fe–Ni from cold spray. In literature analysis are introduced these systems and for each system there is brief description of binary equilibrium diagram. Furthermore here are some short explanations of diffusion, Kirkendall effect and other possible processing technologies of intermetallic materials. In experimental part, samples of sprayed materials were annealed and then microstructural changes were investigated. This thesis contains photographs of microstructure, results from scanning electron microscopy, X-ray, and measurements of microhardness.
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Optimizing the conditions of double electron beam remelting in the process of preparing TBC
Hroš, Michal ; Moravčík, Igor (referee) ; Krajňáková, Petra (advisor)
Thermal barrier coatings (TBCs) are commonly used for thermal protection of components in modern gas turbine application and typically consisting of ceramic top coat and CoNiCrAlY bond coat (BC), both thermally sprayed. Nanostructured CoNiCrAlY bond coatings were deposited onto Ni-based alloy (Inconel 718) by both HVOF and CGDS spraying techniques. Subsequently the deposits were remelted by electron beam up to depth of about 100 m which resulted in removal of defects on the substrate to the bond coat interface. The primary objective of this thesis was to investigation of the influence of parameters used for EB remelting, including multiple remelting on the microstructural changes, phase modification and final state of the coatings. The amount of porosity in the coatings and surface roughness has been evaluated. Scanning electron microscopy and X-Ray diffraction were performed in order to characterize the phase modification before and after the applied treatment. The results indicated that multiple remelting process improved the coating properties in terms of porosity, smooth surface, strength and chemical homogeneity and at last but not least this study demonstrate that low-temperature processing of CoNiCrAlY bond coat represents an interesting and promising alternative for their manufacturing.
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Joining alumina ceramics by thin metallic layers
Poloprudský, Jakub ; Krajňáková, Petra (referee) ; Jan, Vít (advisor)
This bachelor thesis is about the problematics of structural bonds between ceramics and metals with special focus on brazed bonds. First theoretical part describes thoroughly the majority of currently used methods for ceramics joining. Special attention is given to the explanation of phenomenon of bad wettability of ceramics by molten metals and how to solve it. In practical part the work focuses on an analysis of representatives of active and non-active brazing alloys with some added elements. For analysis of microstructures it was necessary to master the basics of preparation of ceramic-metal composite specimens. Important part of the practical section of the work is dedicated to an effort of making a test with comparable results that could be used for ceramic-metal brazed composites evaluation.
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High entropy alloy preparation by means of mechanical alloying
Gamanov, Štěpán ; Krajňáková, Petra (referee) ; Moravčík, Igor (advisor)
This thesis deals with topic of high entropy alloys. The teoretical part explains what are high entropy alloys, how are they different from conventional alloys, how is their chemical composition proposed and what potencial these alloys have. The experimental part describes procedures of preparation of three high entropy alloys witch consists of Co, Cr, Fe, Ni and Ti, where the concentration of all elements except Ti remains the same. These alloys were prepared via mechanical alloying and sintered by SPS process. Crucial part of this thesis is characterization of these three alloys with EDS and XRD supported by hardness measuring and tensile tests.
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Optimizing the conditions of double electron beam remelting in the process of preparing TBC
Hroš, Michal ; Moravčík, Igor (referee) ; Krajňáková, Petra (advisor)
Thermal barrier coatings (TBCs) are commonly used for thermal protection of components in modern gas turbine application and typically consisting of ceramic top coat and CoNiCrAlY bond coat (BC), both thermally sprayed. Nanostructured CoNiCrAlY bond coatings were deposited onto Ni-based alloy (Inconel 718) by both HVOF and CGDS spraying techniques. Subsequently the deposits were remelted by electron beam up to depth of about 100 m which resulted in removal of defects on the substrate to the bond coat interface. The primary objective of this thesis was to investigation of the influence of parameters used for EB remelting, including multiple remelting on the microstructural changes, phase modification and final state of the coatings. The amount of porosity in the coatings and surface roughness has been evaluated. Scanning electron microscopy and X-Ray diffraction were performed in order to characterize the phase modification before and after the applied treatment. The results indicated that multiple remelting process improved the coating properties in terms of porosity, smooth surface, strength and chemical homogeneity and at last but not least this study demonstrate that low-temperature processing of CoNiCrAlY bond coat represents an interesting and promising alternative for their manufacturing.
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|
|
High entropy alloy preparation by means of mechanical alloying
Gamanov, Štěpán ; Krajňáková, Petra (referee) ; Moravčík, Igor (advisor)
This thesis deals with topic of high entropy alloys. The teoretical part explains what are high entropy alloys, how are they different from conventional alloys, how is their chemical composition proposed and what potencial these alloys have. The experimental part describes procedures of preparation of three high entropy alloys witch consists of Co, Cr, Fe, Ni and Ti, where the concentration of all elements except Ti remains the same. These alloys were prepared via mechanical alloying and sintered by SPS process. Crucial part of this thesis is characterization of these three alloys with EDS and XRD supported by hardness measuring and tensile tests.
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|
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Joining alumina ceramics by thin metallic layers
Poloprudský, Jakub ; Krajňáková, Petra (referee) ; Jan, Vít (advisor)
This bachelor thesis is about the problematics of structural bonds between ceramics and metals with special focus on brazed bonds. First theoretical part describes thoroughly the majority of currently used methods for ceramics joining. Special attention is given to the explanation of phenomenon of bad wettability of ceramics by molten metals and how to solve it. In practical part the work focuses on an analysis of representatives of active and non-active brazing alloys with some added elements. For analysis of microstructures it was necessary to master the basics of preparation of ceramic-metal composite specimens. Important part of the practical section of the work is dedicated to an effort of making a test with comparable results that could be used for ceramic-metal brazed composites evaluation.
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Reaction synthesis of bulk intermetallic materials from cold spray deposits from binary powders containing iron
Dyčková, Lucie ; Krajňáková, Petra (referee) ; Jan, Vít (advisor)
This thesis deals with reaction synthesis of materials Fe–Al, Fe–Cu and Fe–Ni from cold spray. In literature analysis are introduced these systems and for each system there is brief description of binary equilibrium diagram. Furthermore here are some short explanations of diffusion, Kirkendall effect and other possible processing technologies of intermetallic materials. In experimental part, samples of sprayed materials were annealed and then microstructural changes were investigated. This thesis contains photographs of microstructure, results from scanning electron microscopy, X-ray, and measurements of microhardness.
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